(1) Fields of the Invention
The present invention relates to a bicycle hub assembly, and more particularly, to a ratchet mechanism for a bicycle hub assembly.
(2) Descriptions of Related Art
The conventional bicycles generally comprise a front wheel with a chainwheel, and a rear wheel with a sprocket, and a chain is connected between chainwheel and the sprocket. The chainwheel is driven by a crank with two pedals, so that when the cyclist treads the pedals, the crank rotates the chainwheel so as to drive the sprocket via the chain, such that the rear wheel drives the bicycle forward. Some of the bicycles are equipped with a ratchet mechanism connected to the hub on the rear wheel so as to drive the rear wheel when the pedals are treaded forward. When the pedals are treaded backward, the pawls of the ratchet mechanism do not drive the rear wheel backward. The conventional hub assembly has a collar with ratchet teeth defined therein, and the pawls, usually are three, are engaged with the ratchet teeth to drive the bicycle. The pawls are positioned by using a resilient ring. When the pedals are treaded backward, the ratchet teeth push the pawls downward so as not to deliver the force to the rear wheel.
Only three pawls cannot effectively engage the ratchet teeth and drives the collar and the rear wheel. Some manufacturers use six pawls to improve the shortcoming, however, the distances between the six pawls are small so that the resilient ring is expanded and released frequently. Unexpected actions of the pawls may happen to affect the operation of the ratchet mechanism. The resilient ring will be malfunctioned due to the frequent actions. The height of the pawls and strength are reduced along with the increase of the number of the pawls are used. The pawls may skip from the engagement with the ratchet teeth, and the pawls may be broken.
The distance between the pawls, the interference of the frequent actions of the resilient ring, and the strength of the pawl become concerns of the manufacturers.
The present invention intends to provide a ratchet mechanism for improving the shortcomings mentioned above.